Among the conventional plasma display panels (to be called hereinafter "PDP"), there is a trigger discharge type PDP of Sony corporation of Japan, which is disclosed in U.S. Pat. No. 4,562,434 and Japanese Laid-Open Patent publication No. Sho 58-30038 which are in turn schematically and extractively illustrated in FIGS. 1 and 2 respectively. This trigger discharge type PDP comprises a front plate Fa, a rear plate Ba, a plurality of X-Y matrix shaped anodes Aa and cathodes Da, and a plurality of separating walls Pa which are disposed between the respective anodes in direction parallel to the anodes Aa so as for the anodes to be separated one another.
Especially, the cathodes Ka disposed in the Y direction are separated from the inner side of the rear plate Ba by a dielectric insulating layer Ia, while trigger electrodes (or auxiliary anode) Ta are disposed between the insulating layer Ia and the rear plate Ba. The trigger electrode Ta,Ta' can be provided in a plurality of parallel strips like the cathodes Ka as shown in FIG. 1 or can be either provided in a single piece having the same size as that of the whole rear plate Ba s shown in FIG. 2.
Such a PDP is constructed such that a auxiliary discharge, i.e., a trigger discharge is generated before the occurrence of a main discharge for triggering the main discharge, and therefore, such a PDP has the advantages that the flickering at the initial stage of the main discharge is prevented, the response characteristics is markedly improved, and the realization of a high resolution image is made possible.
However, the above mentioned trigger discharge is generated through a medium of the dielectric insulating layer disposed between the trigger electrodes Ta and the cathodes Ka, and therefore, if the physical characteristics of the insulating layer is insufficient, then the product can not have the intended quality, thereby possibly leading to production of large quantities of defective products. The reason is that the insulating layer not only serves as the means for separating the cathodes Ka from the trigger electrodes Ta, but also as a means for depositing the wall charges which help to trigger the main discharge. In effect, a sternly precise dielectric constant is required for meeting the product quality and the design figures, while a high strength for withstanding against a voltage breakdown during the discharge is also required.
Further, in order to maintain high contrast ratio in said trigger discharge type PDP, the wall charge depositing region should be broadened so that satisfactory strength of trigger discharge can be obtained. For this purpose, the width of cathode should be formed as narrow as possible so as for the exposed width of dielectric layer to be formed relatively broadly. In this case, the contrast ratio may be raised. But brightness becomes relatively low because main discharge is lowered due to the decrease of the cathode width.
Meanwhile, in the manufacturing processes, a high precision work is also required, and particularly, the flatness of the trigger electrodes Ta should be kept above a predetermined level in order to prevent the concentration of charges on a particular region. Further, as the material of such trigger electrodes Ta, an organic metal paste having gold as the main ingredient is used, and therefore, the manufacturing cost of the product becomes very high.